The present invention relates generally to semiconductor processing techniques. More particularly, the invention includes a method and structure for forming a spatial light modulator with multi-layer landing structures. Merely by way of example, the invention has been applied to a method of forming landing structures from several layers of different materials, with each material characterized by different material properties. The method and structure is applicable to spatial light modulators utilizing various mirror designs. The method and structure can be applied to other applications as well, such as actuators, sensors, detectors, and display components.
Spatial light modulators (SLMs) have numerous applications in the areas of optical information processing, projection displays, video and graphics monitors, and televisions. Reflective SLMs are devices that modulate incident light in a spatial pattern to reflect an image corresponding to an electrical or optical input. The incident light may be modulated in phase, intensity, polarization, or deflection direction. A reflective SLM is typically comprised of a one or two-dimensional array of addressable picture elements (pixels) capable of reflecting incident light. Source pixel data is first processes by an associated control circuit, then loaded into the pixel array, one frame at a time.
Some SLMs are fabricated using micro-electromechanical system (MEMS) architectures. Generally these MEMS devices include multiple components arranged in an array configuration. The components include electrodes, which are actuated to attract or repel an associated moveable mirror. Typically, the moveable mirror is attracted toward a position associated with an electrode upon application of an electrical force and restored to an original position by a restoring force. In the position associated with the electrode, some SLMs reflect light toward a viewing screen, while the SLM reflects light away from the viewing screen in the original position.
In some system architectures, landing structures, also called landing posts or landing pads, are utilized to arrest the motion of the moveable mirror in one or more of the several positions. The reliable operation of some SLM devices as a function of time are hampered by stiction forces, which can cause the moveable mirror to stick to the landing structures. Moreover, in some SLM designs, repeated contact between a moveable mirror and a landing structure results in damage to the mirror and/or the landing structure.
Therefore there is a need in the art for improved methods and structures for SLMs with landing structures.